Structure and Properties of Poly(butylene adipate-co-terephthalate)/ Thermoplastic Starch Blends Manufactured by Elongational Extrusion

Blending with the cheaper and biodegradable thermoplastic starch (TPS) is an effective way to realize low-cost poly(butylene adipate-co-terephthalate)(PBAT). In this work, the PBAT/TPS blends were manufactured by double-axis eccentric rotor extruder (ERE) based on elongational extrusion. And the effects of elongational extrusion on the morphology, crystalline structure, rheological properties and mechanical performance of PBAT/TPS blends were systematically studied through scan electron microscope, capillary rheometer, X-ray diffraction spectrometer, tensile testing machine and charpy impact testing machine. The results indicate that the apparent viscosity of the PBAT/TPS blend manufactured by ERE is higher than that of the blend prepared by twin screw extrusion (TSE) while the viscous flow activation energy and non-Newtonian index of the former are lower than those of the latter due to the heat-degradation of PBAT is relatively low during elongational extrusion. And the elongational extrusion improves the plasticization of starch and its dispersion in PBAT matrix, which enhances the PBAT-TPS interfacial interaction. The tensile strength, elongation at break, and impact strength of the PBAT/TPS blend are increased by 19%, 9% and 28% respectively compared with the PBAT/TPS blend manufactured by TSE. As the TPS content is 40%, the tensile strength of the blend manufactured by ERE only is decreases by 29% compared with that of PBAT. But the blend remains the same elongation at break as PBAT, and its impact strength is 75% higher than that of PBAT, indicating that ERE is an efficient tool to manufacture low-cost and high-performance biodegradable polymer materials. ©2021, Editorial Board of Polymer Materials Science & Engineering. All right reserved.